The values of Kw as a function of temperature are as follows: Is the autoionization of water exothermic or endothermic? Choose the right variant. exothermic endothermic it depends on pressure it depends on temperature b What is the pH of pure water at 50°C? 6.631 From a plot of ln(Kw) versus 1/T (using the Kelvin scale), estimate Kw at 37°C, which is the normal physiological temperature.

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic 

Ithink 2 is the correct

Matter- occupies space and possesses rest massno matter is the opposite

The answers is a nuclear changes